The problem of consumer and medical waste and the residues of industrial production, resulting in environmental pollution, is one of the most significant factors causing serious health problems throughout the world. These wastes include, but are not limited to, plastics, contaminated and natural wood wastes, infectious hospital wastes, rubber tires, electronic wastes, etc.
Concerned institutions and individuals are continually looking for economical environmentally-safe solutions for waste disposal.
For example, U.S. Pat. Nos. 4,116,186, 4,184,437, 4,194,455, 4,261,269, 4,544,374, and 4,561,363 disclose methods and apparatuses for burning waste materials, and particularly, to methods and furnaces wherein the waste is burned and the combustion of the gases formed by pyrolysis takes place in a separate one-compartment combustion chamber.
In the combustion of gases given off by heating the waste, it is very desirable that these gases be burned as completely as possible, thereby avoiding the escape of residual gases which are potentially harmful to the environment.
None of these prior art patents, however, discloses a multi-compartment vortex burning chamber which would allow separation of the solid particles carried by the lean gas and a complete burning of the lean gas, such that the escape of residual gases and the resulting pollution to the environment is substantially minimized if not eliminated altogether. Such a method and system would be very desirable in the disposal of waste materials by combustion.
With this in mind, it is noted that in the technology relating to cyclone furnaces, multiple combustion chambers are well known; however, these cyclone furnaces have not been applied to the complete combustion of lean gases.
For example, in the U.S. Pat. No. 2,747,526, a cyclone furnace for ash-containing solid fuels is disclosed, wherein one or more primary cyclone type combustion chambers are positioned with horizontally extending axes. A tangential fuel and air inlet is provided at (or adjacent to) one end thereof; a tangential top outlet is provided for the gaseous products of combustion; and a bottom outlet is provided for separated molten slag. The products of combustion are discharged tangentially into a second similar fluid cooled cyclone chamber which is arranged with its longitudinal axis at right angles to the axis of the first combustion chamber.
U.S. Pat. Nos. 5,022,320 and 5,052,312 are concerned with a cyclone furnace for hazardous waste incineration and ash vitrification, such that organic hazardous substances are completely destroyed. The municipal waste is delivered to the furnace, and a controlled amount of air is provided through various ports to allow optimum combustion conditions. Bottom and fly ash is formed in the combustion process. The bottom ash is removed from the bottom of the boiler to an ash tank, and the fly-ash is transported to the burner of the cyclone furnace for subsequent vitrification.
The cyclone furnace fires into a secondary furnace which includes a flow restriction to provide gas recirculation and increase residence time for greater destruction of refractory organics and to increase the retention of fine organic particles in the slag. The cyclone furnace is oriented tangentially to the secondary furnace. This orientation increases the combustion gas residence time and inorganic particulate collection efficiency of the slag layer in the secondary furnace.
Although having multi-chamber burners, the latter three patent references disclose cyclone furnaces which need temperatures above the ash fuel temperature, i.e. 2100.degree. F.-2700.degree. F. to create a slag and are not intended for, nor applicable to, the combustion of lean gas (including pyrolysis gas) having a low calorific value. Besides, the diversified multi-chambered burners do not provide for a separation of dust carried along the lean gas. Furthermore, the equipment needs a sophisticated cleaning means.